I have tested in Gather and All mode, but new and stackable items will not enter your backpack even if you have available slots when your inventory is full. I am not sure if this can be adjusted or if the game creates limitations due to the full invetory. 

Thanks,

This is expected. The item must successfully enter your inventory first, in order for Backpacks to detect the item. Any other design would have a significant performance impact and would probably not be worth it.

Thanks you WhiteThunder for the quick reply. That makes perfect sense. Thank you for clarifying. 

Love your plugins, have a great day.